I found this in alt.hackers, supposedly from "scott@spam.Corp.Sun.COM (Scott McNealy)". Here's what the comments at the front of the program say:
/* cc.c - front end for multiplexing a 1-user Solaris compiler license
*
* In Solaris 2.x, Sun has unbundled and licensed the compiler. The
* license is floating, and per-user instead of per process. That is, if
* you have one license, then any one user can run any number of compiles
* at the same time, but a second user can't run any compiles at all.
*
* This program takes advantage of this somewhat unusual setup by running
* all compiles as the same user. The program should be installed setuid
* to root. When run, it changes a few things so that it looks like it is
* some arbitrary user, and then runs the real Solaris compiler.
*
* As long as all users run this instead of using Solaris's cc directly,
* everyone will be able to compile as much as they like with only a
* single-user compiler license.
*
* Some technical notes: It has to be setuid to root instead of to the
* arbitrary normal user because under System V only root can set the real
* uid, and the compiler's license checker looks at the real uid. And
* root itself can't be the user to do compiles, since the license checker
* doesn't allow root to use the compiler at all! The program also makes
* the working directory world-writable during the compile, and changes it
* back afterwards. This is so that the objects or executables can be
* written there by the designated user. However, if you tell cc to write
* objects to another directory, maybe a subdirectory, it won't work. So,
* either don't write into subdirectories, or manually make the destination
* directory world-writable yourself.
*
* This program is probably of limited usefulness. Most people who need a
* compiler under Solaris will just get gcc. However, I found myself in a
* situation where we had a free 1-user copy of the Solaris compiler. Living
* with the limitation was out of the question, and writing this program
* was easier than installing gcc. Maybe in the next release, Sun will
* go to a per-process license and this will stop working, but for now
* it's useful.
*/